Bismuth-and phosphorus-containing catalyst support, reforming catalysts made from same, method of making and naphtha reforming process

ABSTRACT

Bismuth- and phosphorus-containing catalyst supports, naphtha reforming catalysts made from such supports, methods of making both support and catalyst, and a naphtha reforming process using such catalysts.

FIELD OF THE INVENTION

[0001] This invention relates to bismuth- and phosphorus-containingcatalyst supports, naphtha reforming catalysts made from such supports,methods of making both support and catalyst, and to a naphtha reformingprocess using such catalysts.

BACKGROUND OF THE INVENTION

[0002] Catalytic naphtha reforming is an important oil refining processthat converts low-octane paraffins- and naphthenes-rich naphtha tohigh-octane, aromatics-rich C₅+ liquid reformate and hydrogen (H2).Petroleum refiners are always searching for improved reforming catalyststhat afford high selectivity (i.e., high C₅+ liquid and H2 yields), highactivity, low coking rates and high selectivity and/or activitystability. More selective catalysts are desired to maximize theproduction of valuable C₅+ liquid and H2 while minimizing the yield ofless desirable C₁-C₄ gaseous products. Catalysts with acceptableselectivity but higher activity are also desired because they allowoperation at lower reactor inlet temperatures while maintaining the sameconversion (octane) level or allow operation at the same temperature butat higher conversion (octane) level. In the former case, the higheractivity of the catalysts also allows for significant extension of thecycle length and reduced frequency of regeneration. Catalysts thatafford lower coke make rates and higher selectivity and/or activitystability are also very highly desired because they allow forsignificant shortening of the coke burn off and unit turnaround time orfor a longer operation before regeneration.

[0003] Many researchers have devoted their efforts to the discovery anddevelopment of improved reforming catalysts. The original commercialcatalysts employed a platinum-group metal, preferably platinum itself,deposited on a halogen-acidified γ-alumina support; see, for example,Haensel's U.S. Pat. Nos. 2,479,109-110, granted in 1949 and assigned toUniversal Oil Products Company. About 1968, the use of rhenium togetherwith platinum was introduced. Kluksdhal's U.S. Pat. No. 3,415,737teaches Pt/Re catalysts wherein the atomic ratio of rhenium to platinumis between 0.2 and 2.0 and his U.S. Pat. No. 3,558,477 teaches theimportance of holding the atomic ratio of rhenium to platinum to lessthan 1.0. Buss's U.S. Pat. No. 3,578,583 teaches the inclusion of aminor amount, up to 0.1 percent, of iridium in a catalyst having up to0.3 percent each of rhenium and platinum. Gallagher et al's U.S. Pat.No. 4,356,081 teaches a bimetallic reforming catalyst wherein the atomratio of rhenium to platinum is between 2 and 5.

[0004] Phosphorus has been known to increase aromatics yield whenincluded in reforming catalysts since at least since 1959 when Haenseltaught the same in U.S. Pat. No. 2,890,167. In U.S. Pat. No. 3,706,815,Alley taught that chelating ions of a Group VIII noble metal withpolyphosphoric acid in a catalyst enhanced isomerization activity. AndAntos et al's U.S. Pat. Nos. 4,367,137, 4,416,804, 4,426,279, and4,463,104 taught that the addition of phosphorus to a noble-metalreforming catalyst results in improved C₅+ yields.

[0005] In 1974-5, Wilheln's U.S. Pat. Nos. 3,798,155, 3,888,763,3,859,201 and 3,900,387 taught the inclusion of bismuth in aplatinum-group reforming catalyst to improve selectivity, activity andstability characteristics. Antos' U.S. Pat. No. 4,036,743 taught ahydrocarbon conversion catalyst comprising platinum, bismuth, nickel andhalogen components. More recently, Wu et al's U.S. Pat. Nos. 6,083,867and 6,172,273 B1 teach a reforming catalyst of mixed composition orstage-loaded comprising a first catalyst comprising platinum and rheniumon a porous carrier material and a second catalyst comprising a bismuthand silica component.

[0006] Until now, however, no one has taught the benefits of includingboth bismuth and phosphorus in a noble-metal naphtha reforming catalyst.

SUMMARY OF THE INVENTION

[0007] This invention provides for a catalyst support comprisingγ-alumina and small amounts of bismuth and phosphorus incorporatedhomogeneously throughout. The invention further provides for catalystcompositions comprising platinum, chlorine, and optionally rhenium,deposited on such supports. The invention also provides for a method ofmaking such catalyst support and catalyst compositions and for a processfor reforming naphtha to improve its octane using such catalyst. Whenused to catalyze reforming of naphtha, the Bi- and P-containing catalystcompositions of this invention unexpectedly exhibited significantlylower coking rates and C₅+ yields activity activity decline rates; i.e.,higher stability, relative to catalysts containing only either Bi or Ppreviously known.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 shows C₅+ Yield Decline Data for Catalysts A to H.

[0009]FIG. 2 shows Activity Decline Data for Catalysts A to H.

[0010]FIG. 3 shows C₅+ Yield Decline Data for steamed and oxychlorinatedCatalysts D_(SO) and G_(SO).

[0011]FIG. 4 shows Activity Decline Data for steamed and oxychlorinatedCatalysts D_(SO) and G_(SO).

[0012]FIG. 5 shows C₅+ Yield Decline Data for Catalysts I to L.

[0013]FIG. 6 shows Activity Decline Data for Catalysts I to L.

DETAILED DESCRIPTION

[0014] The catalyst support compositions of the present inventioncomprise alumina, primarily γ-alumina, into which small amounts ofbismuth and phosphorus have been incorporated during preparation of thesupport extrusion mixture. It has been found that, for catalysts madefrom such supports, the inclusion of small amounts of both Bi and Pdistributed essentially homogeneously throughout the support results insignificant improvement in the C₅+ yield and activity stability relativeto the conventional catalyst compositions. In addition, these promotersin the support allow for significant suppression of the coking rate andremarkable improvement in the regenerability of the catalyst aftermoisture upset.

[0015] The catalyst compositions of this invention comprise such supportimpregnated with catalytically active amounts of platinum and chlorine,and optionally with a catalytically active amount of rhenium. Thecatalytically effective amount of Pt in the catalyst provides thedesired hydrogenation-dehydrogenation functionality of the catalyst, thecatalytically effective amount of Re (when present) improves the coketolerance and resistance to deactivation, and the catalyticallyeffective amount of Cl enhances the acidity of the support and providesthe desired acidic (isomerization and cracking) functionality. Inclusionof Pt, Re and Cl in a naphtha reforming catalyst is well known in theart. However, when these elements are impregnated onto the supports ofthe present invention, these catalysts exhibit significantly lowercoking rates and higher C₅+ yield and activity stability than catalystscomprising the same elements impregnated onto conventional supports. Thecatalyst compositions of the present invention, therefore, allow for areduction of the frequency of catalyst regeneration and maximization ofunit uptime, reformate production and profitability. In the rare caseswhen higher stability is not desired, these compositions would stillprovide significant cost savings to the refiner because of their lowercoke make rates, shorter coke burn off time and unit turnaround timeduring regeneration relative to conventional catalysts. The lower cokingrates of the compositions of this invention could be of a great benefitto refiners operating the two different types of fixed-bed reformingunits: cyclic and semi-regenerative.

[0016] Support

[0017] The support for the catalyst of the present invention comprisesan alumina that is predominately γ-alumina throughout which effectiveamounts of bismuth and phosphorus have been essentially homogeneouslydistributed.

[0018] Effective amounts of bismuth and phosphorus are distributedthroughout the support particles by incorporation of these promotersinto the support precursor mixture prior to forming the supportparticles, which is usually accomplished by extrusion. Between 0.05 wt.% and 0.1 wt. %, based on the finished catalyst, of bismuth has beenfound to be effective, with between 0.05 wt. % and 0.08 wt. % beingpreferred. Between 0.05 wt. % and 0.6 wt. %, based on the finishedcatalyst, of phosphorus is effective, with between 0.1 wt. % and 0.4 wt.% being preferred, and between 0.25 wt. % and 0.35 wt. % beingparticularly preferred.

[0019] The forming of the support particles may be accomplished by anyof the methods known to those skilled in the art. In the preferredmethod, a mixture comprising approximately 62 wt. % of γ-alumina powderand 38% wt. alumina sol is prepared. The γ-alumina is a high-purityγ-alumina made by digestion of aluminum wire in acetic acid followed byaging to form alumina sol and spray drying of the sol to form thealumina powder. The alumina sol is also prepared as described above(i.e., by digesting aluminum wire in acetic acid and aging) and containsabout 10 wt. % alumina (dry basis), 3 wt. % of acetic acid and theremainder deionized water. The alumina sol is blended with the aluminapowder and acts as a peptizing agent to aid the extrusion of theγ-alumina. Any other methods (other than using alumina sol; for example,using extrusion aids) known to those skilled in the art could also beused to form the alumina carrier particles of this invention. Suchextrusion aids include but are not limited to acids (such as nitric,acetic, citric, etc.) and/or organic extrusions aids (such as methocel,PVI, steric alcohols, etc.) The desired amounts of phosphorus andbismuth are essentially homogeneously incorporated into the finishedsupport by adding to the γ-alumina/alumina sol mixture being blended anamount of phosphorus precursor solution sufficient to provide thedesired concentration of phosphorus on the finished support and then anamount of the bismuth precursor solution sufficient to provide thedesired concentration of bismuth on the finished support. The additionof phosphorus and bismuth solutions is accomplished at a slow ratefollowed by a period of continued blending to ensure homogeneousdistribution of phosphorus and bismuth in the support. The final mixshould be prepared in such a way so that to form an extrudable paste.Well extrudable paste is formed when the LOI (loss on ignition) of themixture is between 30 and 70 wt. %, and more preferably between 45-60wt. %.

[0020] To incorporate the desired amount of phosphorus into the supporta solution of phosphorus precursor is prepared. The solution can beprepared by any of the methods known to those skilled in the art. Thephosphorus precursor is selected from the group comprisingphosphorus-containing acids and salts, for example, H₃PO₄, H₃PO₃, H₃PO₂,NH₄H₂PO₄, (NH4)2HP04, with H₃PO₄ being the most preferred precursor. Thepreferred precursor solution may contain between 50 and 85 wt. % H₃PO₄,with 70-85 wt. % H₃PO₄ being the most preferred.

[0021] To incorporate bismuth into the support in such a way so as toprovide for a homogeneous distribution of the bismuth atoms, it isessential that a bismuth solution having all bismuth cations completelyin solution and not indirectly interacting with each other (via chemicalbonds with other elements) be used. A number of bismuth precursors,including but not limited to Bi(NO₃)₃.5H₂O, BiCl₃, BiOCl, BiBr₃, Biacetate, Bi citrate, and various Bi alcoxides may be used, withBi(NO₃)₃.5H₂O being the most preferred. Solutions of these precursors inwater, water+complexing agents (to improve Bi solubility), acidifiedwater solutions as well as different surfactants or organic solventsolutions may all be used to prepare the Bi-containing supports andcatalysts of the present invention. The acceptable concentration ofbismuth in the solution is dependent on the bismuth precursor chosen,the nature of the solvent and the solubility range for the precursor inthe solvent. The most preferred bismuth solution contains about 9 wt. %Bi (from Bi(NO₃)₃.5H₂O) and approximately 10 wt. % d-mannitol (acomplexing agent) and the balance water. Other complexing or chelatingagents, including but not limited to polyacohols or mixtures ofpolyacohols or alcohols and acids could also be used instead ofd-mannitol to achieve complete dissolution of the bismuth precursor inthe solvent. The same effect could also be achieved by using acidifiedwater solutions of the bismuth precursor.

[0022] The final steps in making the support of the present inventionare forming the paste prepared above into particles of the support,followed by drying and, optionally, calcining. Any of the conventionalsupport shapes, such as spheres, extruded cylinders and trilobes, etc.may be employed. The formed particles may be dried by any of the methodsknown to those skilled in the art. However, drying at low temperature,that is between 110° C. and 140° C. for over 10 hours is preferred.Drying should achieve a final support LOI level in the range of 10 wt. %to 36 wt. %, more preferably 17 wt. % to 36 wt. %. It is preferred thatthe dried support particles then be calcined in order to lower their LOIto between 1 wt. % and 10 wt. %, preferably between 1 wt. % and 7 wt. %.Calcination is done at a temperature between 400° C. and 750° C.,preferably between 550° C. and 700° C. for a period of between 30minutes and 5 hours, preferably between 1 hour and 2 hours.

[0023] The finished supports of the present invention are allcharacterized by having an essentially homogeneous distribution ofbismuth and phosphorus throughout the γ-alumina base material.

[0024] Catalysts

[0025] To form the finished catalysts of this invention, catalyticallyactive amounts of platinum and chlorine, and optionally rhenium, aredeposited on the support by impregnation techniques known to thoseskilled in the art. Between 0.1 wt. % and 1.0 wt. %, based on thefinished catalyst, of platinum has been found to be effective, withbetween 0.15 wt. % and 0.6 wt. % being preferred, and between 0.20 wt. %and 0.30 wt. % being particularly preferred. Between 0.05 wt. % and 2.0wt. %, based on the finished catalyst, of chlorine has been found to beeffective, with between 0.8 wt. % and 1.2 wt. % being preferred, andbetween 0.9 wt. % and 1.1 wt. % being particularly preferred. If rheniumis present, between 0.01 wt. % and 1.0 wt. %, based on the finishedcatalyst, of rhenium has been found to be effective, with between 0.1wt. % and 0.5 wt. % being preferred, and between 0.2 wt. % and 0.45 wt.% being particularly preferred.

[0026] Various Pt, Cl and Re precursors known to those skilled in theart can be used to prepare impregnating solutions and to impregnate thesupport of this invention. Such precursors include but are not limitedto chloroplatinic acid, bromoplatininc acid, ammoniumchloroplatinate,tetrachloroplatinate, dinitrodiaminoplatinum, hydrochloric acid,tetrachloromethane, chloromethane, dichloromethane,1,1,1-trichloroethane, ammonium chloride, perrhenic acid, and ammoniumperrhenate. Any precursor that will decompose in water, therebyproviding the necessary ions for deposition on the support, isacceptable. In addition, the impregnating solution may contain smallamounts of different acids such as nitric, carbonic, sulfuric, citric,formic, oxalic, etc. which are known to those skilled in the art toimprove the distribution of the platinate and, in the case of rhenium,the perrhenate anions on the alumina carrier. The Pt, Cl and optionallyRe concentration of the impregnating solution is determined in such away to achieve the desired concentration of these components on thefinished catalyst. All impregnation techniques known to those skilled inthe art may be used to prepare the catalysts of this invention.

[0027] Process for Reforming Naphtha

[0028] Reforming of hydrotreated naphtha feed may be achieved bycontacting such feed with the catalyst of the present invention in thepresence of hydrogen at elevated temperature and pressure. The operatingconditions are a space velocity between 0.5 hr⁻¹ and 6 hr⁻¹, preferablybetween 1 hr⁻¹ and 3 hr⁻¹, a pressure of between about 0.1 MPa and about3.5 MPa, preferably between 1 MPa and 3 MPa, a temperature between about315° C. and about 550° C., preferably between 480° C. and 540° C., ahydrogen recycle gas to hydrocarbon feed ratio between about 1 mol/moland 10 mol/mol, preferably between about 1.5 mol/mol and 8 mol/mol, andmore preferably between about 2 mol/mol and 6 mol/mol.

EXAMPLES

[0029] The following examples illustrate the preparation of the supportsand catalysts of this invention. A number of examples illustrate the useof such catalysts in reforming of naphtha and compare their performanceto conventional naphtha reforming catalysts. These examples should notbe considered as limiting the scope of this invention.

Example 1

[0030] This example describes the preparation of five catalyst supportsof the present invention, each containing a different concentration ofbismuth.

[0031] Support A was prepared by mixing 1 kg of γ-alumina with 627 g ofalumina sol in a blender for 10 minutes. With the blender running, 9.1 gof 85 wt. % H₃PO₄ were slowly added and blending continued for aboutanother minute. Then, the bismuth solution defined in Table 1 forSupport A was added to the blender and the blending was continued foranother 7 minutes to form an extrudable paste. The paste was extrudedinto 1.6 mm diameter pellets which were dried at 125° C. overnight. Thepellets were then sized to a predominant length of 4 to 6 mm andcalcined at 660° C. for 1.5 hours. The finished Support A had thecomposition shown in Table 1.

[0032] Supports B, C, D and E were prepared in the same manner, exceptthat Solution A was replaced with the solution appropriate for eachsupport as shown in Table 1. TABLE 1 Support A B C D E Solution: gBi(NO₃)₃ · 5H₂O 3.20 1.87 1.49 1.12 0.747 g d-mannitol 1.50 0.90 0.720.54 0.36 g deionized H₂O 10.0 6.0 4.5 3.5 2.5 Finished Support: Bi,wt.% 0.17 0.10 0.08 0.06 0.04 P. wt.% 0.3 0.3 0.3 0.3 0.3 Al₂O₃ BalanceBalance Balance Balance Balance

[0033] A small sample of Support D was sulfided by mounting a fewpellets on the bottom of a glass Petrie dish, adding a drop of 20 wt. %ammonium sulfide solution, closing the glass lid, and allowing thepellets to be exposed to the ammonium sulfide vapors for about 10minutes. During this treatment the bismuth atoms in the extrudatereacted with the ammonium sulfide, yielding dark gray bismuth sulfide.Examination of the sulfided pellets showed them to be uniformly darkgray, in contrast to the milkγ-white un-sulfided pellets, confirmingthat the bismuth atoms were homogeneously distributed throughout thesupport.

Example 2 Comparative

[0034] This example describes the preparation of three conventionalcatalyst supports, Support F comprising alumina containing the sameconcentration of bismuth as Support D of Example 1, i.e., 0.06 wt. %;Support G comprising alumina containing the same concentration ofphosphorus as the supports of Example 1, i.e., 0.3 wt. %; and Support Hcomprising pure alumina.

[0035] Support F was prepared following the procedure described inExample 1 except no H₃PO₄ was added. Support G was prepared followingthe procedure described in Example 1 except no Bi/d-mannitol solutionwas added. Support H was prepared in like manner except neither H₃PO₄nor Bi/d-mannitol solution was added.

Example 3

[0036] This example describes the preparation of five catalysts of thepresent invention, each containing a different concentration of bismuthin its support.

[0037] Five impregnating solutions were prepared, each by mixing 0.77 mlof concentrated HNO₃, 1.97 ml of concentrated (12M) HCl and 0.660 g of asolution of chloroplatinic acid (denoted as CPA, 29.7 wt. % Pt) and 30ml of deionized water. The solutions were stirred and another 120 ml ofdeionized water were added to bring the total volume of each of theimpregnating solutions to 150 ml. The solutions were then placed in a500 ml. graduated cylinder and circulated with the aid of a peristalticpump. In addition, CO₂ gas was bubbled at a very low rate through a gasdispersion tube placed in the bottom of the graduated cylinder and intothe solution. This was done in order to provide HCO₃ ⁻ anions which areknown to those skilled in the art as capable of competing with Pt and Reanions for alumina surface and to provide for better distribution ofthese metals on the alumina support.

[0038] To impregnate each of Supports A-E from Example 1, once thesolution circulation and CO₂ gas bubbling were established, 70 g of thesupport were quickly added to the solution in the cylinder. Theimpregnating solution was then circulated over the support for 3 hrswhile bubbling CO₂ and then the CO₂ gas and the circulation werestopped. The solution was drained and the catalyst was dried at 125° C.for 2 hr and at 250° C. for 4 hrs and then calcined at 525° C. for 1.5hrs. Each of the finished catalysts, designated Catalysts A-Ecorresponding to Supports A-E, were analyzed and found to contain about0.25 wt. % Pt, about 0.95 wt. % Cl and the corresponding amounts of Biand P (See Example 1, Table 1).

Example 4 Comparative

[0039] This example describes the preparation of three conventionalcatalysts.

[0040] Three more impregnating solutions were prepared. These solutionswere identical to those prepared in Example 3 except that 0.754 g of CPAsolution were used instead of the 0.660 g of Example 3. ConventionalSupports F, G and H from Example 2 were impregnated with these solutionsin the same manner as in Example 3. Analysis of the finished catalystsshowed Catalyst F to contain about 0.3 wt. % Pt and 1.0 wt. % Cl on asupport containing 0.6 wt. % Bi, Catalyst G to contain about 0.30 wt. %Pt and 1.0 wt. % Cl on a support containing 0.3 wt. % P, and Catalyst Hto contain about 0.30 wt. % Pt and 0.96 wt. % Cl on a support containingneither Bi nor P.

Example 5

[0041] This example describes the steaming and regeneration viaoxychlorination treatments of Catalyst D from Example 3 and Catalyst Gfrom Example 4.

[0042] Steaming: 40 g quantities of Catalysts D and G were placed instainless steel racks and into a programmable furnace equipped withinlet and outlet lines. The furnace was closed and an airflow wasestablished through the lines and the furnace chamber. The furnacetemperature was then ramped from ambient to 500° C. while maintainingthe airflow. Once 500° C. temperature was reached the airflow was turnedoff and a slow flow of water was established through the inlet line andinto the heated furnace chamber. The water evaporated in the furnacechamber and steam was generated. The catalyst samples were subjected tosteaming in the furnace for 16 hrs to insure significant Ptagglomeration. Then, the water was stopped, the heat was turned off andthe airflow was again established. The samples were then cooled to 150°C. and transferred to an airtight container. Although there was evidenceof Pt agglomeration on both samples, the steamed Catalyst D was muchlighter in color than the steamed Catalyst G (which was darker gray),indicating higher resistance for Pt agglomeration for the Bi- andP-containing Catalyst D of this invention.

[0043] Oxychlorination: Following the steaming treatment, both catalystsamples were subjected to a two-stage oxychlorination treatment. Suchtreatments are known to be able to restore the original high dispersionof the Pt on an alumina support and are extensively practiced by thoseskilled in the art to restore Pt dispersion, activity and selectivity ofspent Pt reforming catalysts. In the first stage, a 2% mol O₂/N₂ plusCl₂ gas carrying H₂O and HCl vapors was passed through the catalyst bedat 500° C. for 5.5 hrs. In the second stage, the Cl₂ gas was turned offand 2% mol O₂/N₂ gas carrying H₂O and HCl vapors was passed through thecatalyst bed for another 5.5 hrs. The purpose of the first stage was toredisperse the Pt on the support to a level similar to that of the freshcatalyst, whereas the purpose of the second stage was to adjust the Clto the desired level. The steamed and oxychlorinated sample of CatalystD was designated Catalyst D_(SO) and the similarly treated sample ofCatalyst G was designated Catalyst G_(SO). A visual inspection ofCatalyst D_(SO) revealed the absence of grayish colored pellets,indicating no agglomerated Pt. In contrast, the inspection of CatalystG_(SO) revealed the presence of grayish colored pellets. This indicatesthat the Bi- and P-containing Catalyst D of this invention betterpreserves and restores its Pt dispersion upon steaming andoxychlorination treatments than the conventional Catalyst G whichcontained phosphorus but no bismuth. Both catalysts were analyzed andfound to contain very similar levels of Cl (0.83 wt. % and 0.81 wt. %,respectively).

Example 6

[0044] This example describes the preparation of a Pt- and Re-containingcatalyst of this invention.

[0045] An impregnating solution was prepared from 0.50 ml ofconcentrated HNO₃, 1.89 ml of concentrated (12M) HCl and 0.660 g of asolution of CPA (29.7% w Pt), 0.302 g of NH₄ReO₄ and 50 ml of deionizedwater. The solution was stirred and more deionized water was added tobring the total volume of the solution to 150 ml. The solution was thenplaced in a 500 ml graduated cylinder and circulated with the aid of aperistaltic pump. In addition, CO₂ gas was bubbled at a very low ratethrough a gas dispersion tube placed in the bottom of the graduatedcylinder and into the solution. Once the solution circulation and CO₂gas bubbling were established, 70 g of Support D from Example 1 wasadded to the impregnating solution. The impregnating solution wascirculated over the support for a period of 3 hrs while bubbling CO₂ gasand then the CO₂ and the circulation were stopped. The solution wasdrained and the catalyst was dried at 125° C. for 2 hr and at 250° C.for 4 hrs and calcined at 525° C. for 1.5 hrs. The finished catalyst wasdesignated Catalyst I and on analysis was found to contain about 0.25wt. % Pt, 0.26 wt. % Re, 0.99 wt. % Cl, 0.06 wt. % Bi, 0.30 wt. % P andthe remainder alumina.

Example 7 Comparative

[0046] This example describes the preparation of samples of Pt- andRe-containing catalysts on conventional supports F, G and H of Example2.

[0047] A sample of Supports F, G and H were each impregnated using theimpregnating solution and procedure described in Example 6. The finishedcatalyst made from Support F, designated Catalyst J, was analyzed andfound to contain 0.26 wt. % Pt, 0.24 wt. % Re, 0.06 wt. % Bi and 0.95wt. % Cl. The finished catalyst made from Support G, designated CatalystK, was analyzed and found to contain 0.25 wt. % Pt, 0.25 wt. % Re, 0.3wt. % P and 0.98 wt. % Cl. The finished catalyst made from Support H,designated Catalyst L, was analyzed and found to contain 0.25 wt. % Pt,0.25 wt. % Re and 0.96 wt. % Cl.

[0048] The following examples measure and compare the performance of thecatalysts prepared above. In measuring catalyst performance in thereforming of naphtha, three terms are employed—selectivity, activity andstability:

[0049] “Selectivity” is a measure of the yield of C₅+ liquids, expressedas a percentage of the volume of fresh liquid feed charged.

[0050] “Activity” is a measure of the reactor temperature required toachieve the target product octane.

[0051] “Stability” is a measure of a catalyst's ability to sustain itsselectivity and activity over time.

[0052] It is expressed as and is inversely proportional to theselectivity and activity decline rates.

[0053] “Coking Rate” is a measure of the tendency of a catalyst to makecoke on its surface during the reforming process. Because reformingcatalysts deactivate by a mechanism of coke deposition, catalysts withlower coking rates usually exhibit lower C5+ yield and Activity declinerates; i.e., higher stability than catalysts with higher coking rates.

Example 8 Comparative

[0054] This example compares the performance of Catalysts A to H whenused to reform a full range (C₅-C₁₂ hydrocarbons) commercialhydrotreated naphtha feed having a paraffins/naphthenes/aromatics(P/N/A) content of 51/34/15 wt. %, respectively.

[0055] All tests were done in stainless steel micro-reactors operatingunder pseudo-adiabatic and once-through H₂ regime and equipped with feedand product tanks and an online full product (H₂+C₁-C₁₂ hydrocarbons)gas chromatograph analyzer. The catalysts were loaded in themicro-reactors as whole particles (not crushed). In each test, 38 cc ofcatalyst and 38 cc of SiC (an inert diluent) were loaded in themicro-reactor in four stages as shown in Table 2. TABLE 2 StageCatalyst, cc. SiC, cc 1 (inlet) 1.9 17.1 2 5.7 13.3 3 11.4 7.6 4(outlet) 19.0 0

[0056] The feed was doped with isopropanol and 1,1,1-thrichloroethane toprovide the desired target levels of 20 ppmv of H₂O and 1 ppmv of Cl inthe gas phase. The “extra” (unwanted) water in the feed was removedprior to the test by passing the feed trough a vessel filled with 4Amolecular sieve. The tests were conducted as constant-octane (99 C₅+RON) deactivation (Stability) tests at 2.4 hr⁻¹ LHSV, 1.03 MPa and 3 molH₂/mol HC. These conditions, as well as the above catalyst loadingarrangement were chosen in order to force the catalyst to perform harderand decline faster. In order to maintain the product octane (C5+RON) atconstant level throughout the run the reactor wall temperature wasadjusted as needed to correct for the Activity decline.

[0057]FIGS. 1 and 2 show the C₅+ yield decline and Reactor WallTemperature (Activity decline) data, respectively, for Catalysts A to H.Table 3 shows the corresponding Activity and C₅+ yield decline rates andCoking rates. The analysis of the data reveals that the Bi-containingCatalyst F exhibited the lowest Coking Rate and C₅+ yield and Activitydecline (i.e., the highest Stability) among the conventional catalysts.Also, comparison of the data for Catalysts G and H reveals that theaddition of P to the carrier provides somewhat better C₅+ yields butdecline and Coking rates similar to the pure alumina-supported CatalystH. Therefore, the addition of P alone does not suppress the Coking Rateand does not improve the Stability of reforming catalysts. In contrast,comparison of the decline data for the Bi- and P-containing catalysts ofthis invention shows that their Coking rates and decline rates dependvery strongly on the Bi concentration. Surprisingly, Catalysts B, C andD, containing 0.10 wt. % to 0.06 wt. % Bi and 0.3 wt. % P exhibitedsignificantly lower Coking rates and C₅+ yield and Activity declinerates; i.e., higher Stability relative to the catalysts made fromsupports containing Bi-only, P-only, and pure alumina, Catalyst F, G andH. These data demonstrate that the inclusion of the properconcentrations of both Bi and P in a carrier used to make naphthareforming catalysts has a synergistically beneficial effect on CokingRate and performance. TABLE 3 Ave. Hourly Decline Rates CatalystPt/Bi/P, wt. % Activity, ° C./hr. C₅ + Yield, vol. %/hr. Coking Rate,wt. %/hr. A 0.25/0.17/0.3 +0.357 −0.069 +0.074 B 0.25/0.1/0.32 +0.270−0.043 +0.058 C 0.25/0.07/0.28 +0.270 −0.034 +0.054 D 0.26/0.06/0.29+0.258 −0.045 +0.052 E 0.26/0.04/0.3 +0.332 −0.056 +0.068 F 0.24/0.06/0+0.300 −0.054 +0.061 G 0.3/0/0.3 +0.458 −0.087 +0.072 H 0.3/0/0 +0.390−0.095 +0.074

[0058] Conventional catalysts such as Catalysts F, G and H are primarilyused in cyclic reformer units where they are subjected to high severityoperating conditions (low pressure and sometimes high moisture level inrecycle gas). Under these conditions, the catalysts exhibit highercoking rates, i.e. rapid deactivation and require frequent (once every1-2 weeks) regeneration. Catalysts B, C and D of the present inventionwill allow for significantly better yields and Activity stability andsignificant extension of the time on stream before the need forregeneration relative to conventional catalysts. In addition, in therare cases when longer run length is not desired, catalysts of thepresent invention will allow for significant reduction of thecoke-burn-off and reactor turnaround time thus again providing somelonger unit uptime and higher profitability.

Example 9 Comparative

[0059] This example compares the performance of the steamed andoxychlorinated Catalysts D_(SO) and G_(SO) from Example 5.

[0060] The operating conditions and catalyst loadings were as describedin Example 8. FIGS. 3 and 4 show the C₅+ yield and Activity declinecurves, respectively, obtained in these tests. The test data show thatCatalyst D_(SO) significantly outperformed conventional Catalyst G_(SO)affording remarkably lower C₅+ yield and Activity decline rates, lowercoke make rates and much higher C₅+ yield and Activity stabilityadvantage than the one observed for fresh catalysts (see Example 8).

[0061] This suggests that after very high unit moisture upset the Ptdispersion and the performance of Catalyst D of this invention will bemuch more readily restorable (via regeneration) than that ofconventional Catalyst G.

Example 10 Comparative

[0062] This example compares the performance of a Pt- and Re-containingcatalyst of the present invention (Catalyst I from Example 6) againstconventional Pt- and Re-containing catalysts (Catalysts J, K and L fromExample 7).

[0063] Samples of all four catalysts were used to catalyze the reformingof a full range commercial hydrocracked naphtha having a P/N/A contentof 66/21/13 wt. %, respectively. The tests were conducted using the sameequipment and under the same conditions as described in Example 8. FIGS.5 and 6 show the C₅+ yield and reactor wall temperature (Activitydecline) curves, respectively, for Catalysts I to L. Table 4 shows thecorresponding Activity and C₅+ yield decline rates and coking rates.

[0064] The analysis of the data shows that Catalyst I of the presentinvention afforded significantly lower coking rates and lower C₅+ yieldsand activity decline rates; i.e., higher stability, relative toconventional Catalysts J to L. Thus, the data clearly show that theaddition of the proper concentrations of both Bi and P to the supportsof noble metal-containing catalysts results in a synergistic improvementin catalyst performance. It is obvious that Catalyst I of this inventionwill allow the refiner to operate at significantly lower temperatureswhile maintaining C₅+ yield and achieving the desired octane level(conversion). In addition, in this particular case, Catalyst I willallow for significant extension of the run length, i.e. increased unituptime and profitability. Catalyst I will also allow the refiner toincrease profitability by increasing the unit throughput (feed spacevelocity) while still operating at acceptable reactor inlettemperatures, thereby producing more reformate with same octane per unitof time relative to the conventional catalyst systems. Catalyst I wouldbe especially desirable for reformer units that are Activity limited.TABLE 4 Ave. Hourly Decline Rates Activity, C₅+ Yield, Coking Rate,Catalyst Pt/Re/Bi/P, wt. % ° C/hr. vol. %/hr. wt. %/hr. I0.25/0.26/0.06/0.3 +0.184 −0.016 +0.070 J 0.26/0.24/0.06/0 +0.284 −0.035+0.076 K 0.25/0.25/0/0.3 +0.247 −0.020 +0.074 L 0.25/0.25/0/0 +0.281−0.027 +0.075

I claim:
 1. A catalyst support comprising γ-alumina particles throughoutwhich catalytically effective concentrations of bismuth and phosphorushave been essentially homogeneously distributed.
 2. The catalyst supportof claim 1 wherein the concentration of bismuth is between 0.05 wt. %and 0.1 wt. % and the concentration of phosphorus is between 0.05 wt. %and 0.6 wt. %.
 3. The catalyst support of claim 1 wherein theconcentration of bismuth is between 0.05 wt. 2% and 0.1 wt. % and theconcentration of phosphorus is between 0.1 wt. % and 0.4 wt. %.
 4. Thecatalyst support of claim 1 wherein the concentration of bismuth isbetween 0.05 wt. % and 0.1 wt. % and the concentration of phosphorus isbetween 0.25 wt. % and 0.35 wt. %.
 5. The catalyst support of claim 1wherein the particles are extrudates.
 6. A process for making a catalystsupport comprising: a) preparing a solution comprising a bismuthprecursor and a solution comprising a phosphorus precursor; b) preparinga mixture of γ-alumina and alumina sol; c) blending the mixture of step(b) with the solutions prepared in step (a), thereby making a supportprecursor having phosphorus and bismuth distributed essentiallyhomogeneously throughout; d) forming the support precursor intoparticles; and e) drying and calcining the particles.
 7. The process ofclaim 6 wherein the bismuth precursor is selected from the groupconsisting of Bi(NO₃)₃.5H₂O, BiCl₃, BiOCl, BiBr₃, Bi acetate, Bicitrate, and Bi alcoxides.
 8. The process of claim 6 wherein the bismuthprecursor is Bi(NO₃)₃.5H₂O.
 9. The process of claim 6 wherein thephosphorus precursor is selected from the group consisting of H₃PO₄,H₃PO₃, H₃PO₂, NH₄H₂PO₄ and (NH₄)₂HPO₄.
 10. The process of claim 6wherein the phosphorus precursor is H₃PO₄.
 11. The process of claim 6wherein the mixture of γ-alumina and alumina sol comprises about 62 wt.% γ-alumina and the remainder alumina sol.
 12. A catalyst support madeby the process of claim
 6. 13. A naphtha reforming catalyst comprisingthe catalyst support of claim 1 and catalytically effective amounts ofplatinum and chlorine.
 14. The catalyst of claim 13 further comprising acatalytically effective amount of rhenium.
 15. The catalyst of claim 13wherein the amount of platinum is between 0.1 wt. % and 1 wt. % of thecatalyst and the amount of chlorine is between 0.05 wt. % and 2 wt. % ofthe catalyst.
 16. The catalyst of claim 13 wherein the amount ofplatinum is between 0.15 wt. % and 0.6 wt. % of the catalyst and theamount of chlorine is between 0.8 wt. % and 1.2 wt. % of the catalyst.17. The catalyst of claim 13 wherein the amount of platinum is between0.2 wt. % and 0.3 wt. % of the catalyst and the amount of chlorine isbetween 0.9 wt. % and 1.1 wt. % of the catalyst.
 18. The catalyst ofclaim 13 wherein the amount of platinum is between 0.1 wt. % and 1 wt. %of the catalyst and the amount of chlorine is between 0.05 wt. % and 2wt. % of the catalyst, and wherein the catalyst further comprisesbetween 0.01 wt. % and 1 wt. % of rhenium.
 19. The catalyst of claim 13wherein the amount of platinum is between 0.15 wt. % and 0.6 wt. % ofthe catalyst and the amount of chlorine is between 0.8 wt. % and 1.2 wt.% of the catalyst, and wherein the catalyst further comprises between0.1 wt. % and 0.5 wt. % of rhenium.
 20. The catalyst of claim 13 whereinthe amount of platinum is between 0.2 wt. % and 0.3 wt. % of thecatalyst and the amount of chlorine is between 0.9 wt. % and 1.1 wt. %of the catalyst, and wherein the catalyst further comprises between 0.2wt. % and 0.45 wt. % of rhenium.
 21. The catalyst of claim 13 wherein:the concentration of bismuth in the catalyst support is between 0.05 wt.% and 0.1 wt. % and the concentration of phosphorus in the catalystsupport is between 0.25 wt. % and 0.35 wt. %; and the amount of platinumis between 0.2 wt. % and 0.3 wt. % of the catalyst and the amount ofchlorine is between 0.9 wt. % and 1.1 wt. % of the catalyst.
 22. Thecatalyst of claim 13 wherein: the concentration of bismuth in thecatalyst support is between 0.05 wt. % and 0.1 wt. % and theconcentration of phosphorus in the catalyst support is between 0.25 wt.% and 0.35 wt. %; the amount of platinum is between 0.2 wt. % and 0.3wt. % of the catalyst and the amount of chlorine is between 0.9 wt. %and 1.1 wt. % of the catalyst; and the catalyst further comprisesbetween 0.2 wt. % and 0.45 wt. % of rhenium.
 23. A catalyst made by aprocess comprising impregnating the catalyst support of claim 12 withcatalytically effective amounts of platinum and chlorine.
 24. Thecatalyst of claim 23 further comprising impregnating the catalystsupport with a catalytically effective amount of rhenium.
 25. A processfor reforming hydrotreated naphtha comprising contacting said naphthawith the catalyst of claim 13 in the presence of hydrogen at elevatedtemperature and pressure.